Similar presentations

3
Global Precipitation Climatology Project (GPCP) http://www.gewex.org/gpcp.html Most rain falls near the equator. Notice how dry it is on the west coast of the US and South America. The Eastern US is relatively wet.

4
Gravity Air resistance A fallen drop stops speeding up when gravity is balanced by air resistance. The speed that a drop must fall so air resistance is large enough to balance gravity is the terminal velocity. Large drop have much larger terminal velocities than small drops. In fact the reason cloud drops dont fall from the sky is that their terminal velocities are so slow (like 1 inch per minute) that any small updraft can easily keep them suspended.

6
Stepped Art Fig. 7-5, p. 169 Conditionally unstable atmosphere. The atmosphere is conditionally unstable when unsaturated, stable air is lifted to a level where it becomes saturated and warmer than the air surrounding it. If the atmosphere remains unstable, vertical developing cumulus clouds can build to great heights. The rain drop falls out of the cloud when its terminal velocity exceeds the mean updraft speed.

7
Super cooled liquid water drops are droplets that are present at temperature between -40 o C and 0 o C. The freeze on contact with either another particle, tree branch, airplanewing, and make rime ice.

23
Warm air typical has more moisture than cold air giving larger snow flakes.

24
Precipitation Types Sleet: air below freezing, then travels through a layer of air above freezing, begins to melt and then falls through a layer of air below freezing just above the ground surface. Freezing Rain: ground surface is freezing as rain hits the surface it freezes.

45
Somewhat like police radar, Doppler radar can also determine the storm velocity away from or towards the radar station by measuring the frequency difference between the transmitted and reflected signal. Here m/s stands for meters per second. 60 m/s =130 mph The figure shows a tornado. The purple region is moving rapidly towards the station and then 200 meters to the right the pink is moving rapidly away from the station.